# Angles Inside, Outside, and On Circle

Topic:
Angles, Circle

## Part 1: Use the applet above to investigate the measure of an angle formed INSIDE a circle.

Move point C so that it lies somewhere INSIDE your circle (but is not at the center of the circle). Using the calculated measure of the angle the the calculated measures of the intercepted arcs, hypothesis a formula for finding the measure of any angle INSIDE a circle. Move point C again to test your formula.

## How would you calculate the measure of an angle formed INSIDE a cirlce?

Write a formula to calculate the measure of INSIDE Angle A, with intercepted arcs BC and DF.

## Part 2: Use the applet above to investigate the measure of an angle formed OUTSIDE a circle.

Move point C so that it lies somewhere OUTSIDE your circle (but is not at the center of the circle). Using the calculated measure of the angle the the calculated measures of the intercepted arcs, hypothesis a formula for finding the measure of any angle INSIDE a circle. Move point C again to test your formula.

## How would you calculate the measure of an angle formed OUTSIDE a circle?

Write a formula to calculate the measure of OUTSIDE Angle A, with intercepted arcs BC and DF.

## Part 3: Use the applet to investigate the meausure of an angle formed ON a circle.

Using the calculated measure of the angles the the calculated measures of their intercepted arcs, hypothesis a formula for finding the measure of any angle ON a circle. Move point C again to test your formula.

## How would you calculate the measure of an angle formed ON a circle?

Write a formula to calculate the measure of ON Angle CDF, with intercepted arc CD. What angle formula does this remind you of?